Multi-laminate cushioning material



July 9, 1968 M. A. CHAVANNES MULTI-LAMINATE CUSHIONING MATERIAL OriginalFiled July 19, 1962 5 Sheets-Sheet 1 R m v m July 9, 1968 M. A.CHAVANNES 3,3

MULTI LAMINATE CUSHIONI NG MATERIAL Original Filed July 19, 1962 3Sheets-Sheet 2.

-i E 22 Z? INVENTOR.

6' Z -T- 1 4 4442c 4 cwam/wss July 9, 1968 M. A. CHAVANNES 3,

MULTI LAMINATE CUSHIONING MATERIAL Original Filed July 19, 1962 3Sheets$heet 5 INVENTOR. MARC ,4. dmvm/A/ss United States Patent ABSTRACTOF THE DISCLOSURE An improved multi-Iaminate cushioning material formedof two laminates each including a high density plastic and a low densityplastic and wherein atleast one of the "laminates has embossed areassurrounded by uneinbo'ssed areas and the other laminate is sealed to theunembossed areas of the first laminate.

This is a divisional application of Ser. No. 210,902,

filed July 19, 1962, and issued as US. Patent No. 3,285,- 793, on Nov.15, 1966. This invention relates to embossed multiple laminatedmaterials and more specifically embraces a new and improved method andapparatus for the production of multi-laminate embossed materials whichare useful among other things for protective and cushioningapplications, requiring a high degree of tensile strength, resistance tochemicals, fire and smoke, and imperviousness to gases and vapors.

Manufacture of laminated cushioning materials has been generallyaccomplished by the use of adhesives, or

' by heating the surface of the basic layers of thermoplastics, to bebrought in contact, to a tacky state and then joining them underpressure. This invention constitutes an improvement over prior knownprocesses and apparatus which not only facilitates the manufacture ofnew laminated cushioning materials, but also provides an improvedresultant product of greater strength, durability and versatility.

Another objective of this invention encompasses the provision of a newand improved method and apparatus wherein a laminate used in theproduction of cushioning material contains at least one layer serving asa special carrier, permitting other laminae to be preheated safely to arelatively high degree and assuring a complete bond with an overlyinglayer to form a unitary laminate.

A further objective of the invention entails the provision of a new andimproved method and apparatus for making laminated materials that ischaracterized by its simplicity, the attainment of a good bond andrelatively low cost.

A still further objective of this invention resides in the provision ofa new and improved cushioning material wherein the advantageousproperties of plastics normally used are still further enhanced andreinforced.

A still further objective of this invention is manifested A stillfurther objective of the invention resides in the provision of a new andimproved cushioning material.

3,392,081 Patented July 9, 1968 The above and further objectives andadvantages of this invention will become more apparent from thefollowing description and supporting drawings forming part of thisapplication.

In the drawings;

FIG. 1 is a diagrammatic illustration of one embodiment of theinvention.

FIG. 2 is a perspective view of apparatus in accordance with theinvention for laminating plastic materials.

FIG. 3 is a perspective view of a modified embodiment of apparatus forlaminating plastic materials. j

FIG. 4 is a diagrammatic illustration of apparatus" for drying thelaminate produced by the apparatus shown in FIGS. 2 and 3.

FIG. 5 is a fragmentary cross-sectional view of the plastic layer priorto lamination and taken along the line 55 of FIG. 2.

FIG. 6 is a fragmentary cross-sectional view of the resultant laminatedmaterial and taken along the line 6-6 of FIG. 4.

FIG. 7 is a cross-sectional view of an embossed cushioning material inaccordance with the invention.

FIG. 8 is an elevational view of a portion of the vacuum embossingroller shown in FIG. 1.

FIG. 9 is a fragmentary cross-sectional view of the vacuum embossingroller shown in FIG. 8 and taken along the line 9-9 thereof.

FIG. 10 is a magnified cross-sectional view of the surface of the vacuumembossing roller of FIG. 8 carrying a section of embossed cushioningmaterial in ac cordance with the invention.

Broadly, the process in accordance with theinvention concerns animproved method and apparatus for manufacturing cushioning materialutilizing two composite layers of plastic material, at least one ofwhich is embossed and the other is sealed to the embossed layer to forma plurality of sealed air cells. Through the utilization of thecomposite sheets of material, wherein said sheets each consist of alayer of a plastic material having a relatively high melting point and alayer of material having a relatively low melting point, it is possibleto heat these two composite sheets to bring the low melting point layersto a temperature that will insure fusion between the two sheets withoutthe need for careful temperature control in preheating the sheets, whichhas heretofore been necessary to avoid damage or distortion of thesheets during the fabricating process. With the utilization of compositesheets, it is possible to select materials for each layer that will notonly enable the attainment of the advantages outlined above but willalso provide a more durable material having reduced porosity to gasesand moisture.

The invention further contemplates an improved method and apparatus forproducing composite plastic sheets which insure a positive bond betweenthe layers of each composite sheet and enables the lamination to beaccomplished continuously and as one step in the process for producingthe resultant cushioning material. The fabrication of cushioningmaterials utilizing two sheets of plastic material wherein at least oneof said sheets was embossed has presented a problem in effecting carefulcontrol of the temperature. With this invention, one of the layers ofeach composite sheet is used as a carrier for the second layer and in sodoing, it is possible to heat the second layer to a temperature abovethe actual melting point without damaging or otherwise distorting it.

In this way, even though the second layer may be cooled to some degreeprior to the sealing of the sheets, one to the other, the layers of thesheets which are brought into contact can be easily maintained at thefusing temperature.

lamina will be described.

Although a large variety of plastic combinations may be used in themanufacture of a multi-laminate-cushioning material, for the purpose ofclarity, the initial lamina will be identified throughout thespecification as a low density ethylene polymer and the plastic coating11 shall be identified as a vinylidene chloride polymer. In thisembodiment of the invention, lamination is accomplished by a bath 12containing a plastic emulsion 13 through which the lamina 10 is conveyedby means of a feed roller 14 feeding the lamina onto a relatively largerroller 15, the latter being partially immersed in the emulsion 13. Aneven and smooth distribution of the emulsion 13 on the lamina 10 isassured by the action of an air doctor 16 which removes excessiveemulsion. The coated web '17 is then conveyed over a second roller 18and then to drying apparatus 25.

A perspective view of this method of applying a film of plastic to acontinuous web is shown in FIG. 2 having portions of the bath 12 cutaway to allow a clearer insight into the apparatus for immersing the web10in the emulsion 13.

Another method of applying a film of one plastic to a continuous layerof another plastic is shown in FIG. 3, wherein'a plurality of rotarybrushes 19 are supplied with a plastic emulison 13 through feeder tubes20. The bristles 21 of the rotary brushes 19 spread an even film of theplastic emulsion on one surface of the lamina 10 as it is conveyedbeneath the rotary brushes. It is understood, of course, that a similarend may be obtained by spraying the emulsion against one surface of theplastic laminate or by any suitable method. Furthermore, a laminate oftwo distinctive continuous sheets of plastic could be produced byadhering the two layers to each other by introducing an adhesive. Inthis connection, a variety of epoxy resins and a number of elastomerssuch as polymerized chloroprene or neoprene have shown very satisfactoryresults.

After the emulsion 13 has been applied to the continuous-lamina 10 byany of the preceding methods, the coated lamina 17 is conveyed infestoon fashion over a plurality of rollers 22 in order to increase thedrying area, while hot air is supplied through pipe 24, having aplurality of openings 24' correlated in position with each loop ofmaterial and facing downwardly into the spaces provided by the festoons.When used in connection with a combination of polyethylene andvinylidene chloride polymer, the heated air would be maintained at atemperature of approximately 100 to 130 F., and preferably at about 110F. The festoons 25 may be approximately eight feet deep, and about fiveminutes drying time would be required at the suggested temperatures. Inthis manner, drying operations may be carried out within a small areaand'at relatively high speeds. A more detailed sketch of the dryingapparatus in operation is shown in cross-section in FIG. 4.

The second lamina 10' may be processed in substantially the same manneras illustrated and described in connection with lamina 10, and elementsof the apparatus for coating the lamina 10 have been identified by likeprimed numerals. The emulsion 11' may be dried in the same mannerillustrated and described in connection with the lamina 11 or both thelamina 11 and 11' may be dried by the utilization of radiant energy. Forthis purpose, a radiant heater 23 (see FIG. 1) would be disposed 4 a inproximity to the lamina to be dried, and energy applied by means ofappropriate conductors 23a and 23b. The radiant heater may take anydesired form depending on the specific wave length required to effectthe drying operation. If desired, the lamina to be dried'may be passedthrough an appropriate oven containing heating lamps or other types ofheat radiators or generators for imparting heat to the layer 11 or 11"as the case may be at a'rate and for a period of time that willcompletely dry the layer prior to preheating of the'lamina 26 or 26' forapplication to the embossing and laminatingroller 32. Radiant heat mayalso be obtained by utilization of a suitable fluid heater wherein ahigh temperature liquid or gas is fed an appropriate radiator.

A cross secti on of the initiallamina 10 is "illustrated in FIG. 5,while a cross section of the resultant laminate 26 is shown in FIG; 6.

Subsequent to drying operations, the two laminae 26 and 26"described areconveyed over cooperating and synchronized systems of rollers to anembossing roller for further processing. Rollers 27 and 27 are arrangedto feed the two laminae to two sets of rollers 28 and 31 and 28' to 31which are internally heated at successively increasing temperatures forgradually heating the plastic layers at' least to the fusing temperatureof the plastic having a lower melting point.

Speaking in terms of a laminate having the combination of a relativelylow density polyethylene of one mil thickness and a vinylidene chloridepolymer, such as saran of .2 mil thickness, the successive increase intemperature would be arranged approximately in the following manner:Rollers 28 and 28' havinga large diameter such as 24" to provide moresurface allowing sufficient time for the cold web to absorb thefirstsubstantial temperature change, would have a temperature of about F.Rollers 29 and 29 of a lesser diameter such as 12" would be preheated toa temperature of 200 F. Rollers 30 and 30' having a diameter ofapproximately 8 would have a temperature of 220 F. and roller 31 havinga diameter of approximately 6" would be preheated to 240 F.; whileroller 31 would be preheated to a temperature of 265 F. A low densitypolyethylene has a melting point of about 230 F., while a vinylidenechloride melts at about 375 F. Since the melting point of thepoly-vinylidene chloride is never reached, this layer serves during theprocess of manufacture as a carrier for the polyethylene, the meltingpoint of which is exceeded on rollers 31 and 31'.

While both laminates 26 and 26' pass very rapidly over the increasinglyheated rollers, the temperature of the roller 31', being only 10 abovethe melting point of the polyethylene, is sufficient to place thepolyethylene in afusable state in which it can be easily embossed with aplurality of depressions as it passes over the surface of the embossingroller 32 at 33. The second lamina 26 may be heated on roller 31 to asubstantially higher degree than the melting point of the polyethylenein order to insure absolute fluidity of at least the exposed surface ofthe polyethylene as it is brought in contact with the correspondinglayer of polyethylene of lamina 26 immediately subsequent to embossment.If desired, a radiant heater may be utilized to maintain the temperatureof the layer 10' on the embossing roller after it leaves the roller 31'and prior to application of the second lamina 26.

This procedure assures a coalescent fusion between the two polyethylenelayers as they are brought in contact on the embossing roller 32 at 34.Since the meeting surfaces of the polyethylene layers are generallyabove the fusion temperature, only very light pressure of the order ofeight to ten pounds is needed at 34 to produce a coalescent unionbetween these layers. This method makes operation at high speedspossible. In actual practice, continuous speeds of approximately 300 to500 ft'. per minute and even higher may be attained. The compressedmaterial is subsequently cooled by a water spray or similar means andthe finished material 36 is then stripped off the embossing apparatus byroller 35 and conveyed to a suitable receiver.

Embossment of the laminate 26 on roller 32 is preferably accomplished byvacuum means communicating with each individual depression 37 on thesurface of the embossing roller as indicated in FIGS. 8 and 9. In theembodiment shown, the hemispherical depressions 37 are connected bypassages 38 connecting with the vacuum manifold 39 of the embossingroller 32. The surface of the roller surrounding the depressions 37 ispreferably covered with a silicone material 40 to prevent possibleadhesion of the highly preheated laminate to the surface of the moldingroller during operation. Although the drawings indicate a hemisphericalshape, both in the depressions 37 on the surface of the embossingrollers, as well as in the magnified cross-section 36 on the finishedproduct, it is understood that the size, configuration, depth, symmetryand distribution of the embossments may be modified to suit anypractical purpose or requirement.

An enlarged view of a section of the multi-laminate 36 while inengagement with the roller 32 is shown in FIG. 10. It is easilydiscernible here that the polyethylene layers and 19' retain theiridentity in both composite sheets throughout the area of embossrnent,whereas the polyethylene is united in one coalescent layer throughoutthe area of fusion 41. This phenomena can also be observed in thecross-section of the finished material 36 as shown in FIG. 7.

As pointed out earlier, the combination of polyethylene and polymerizedvinylidene chloride was described in accordance with the method andresultant products of this invention, since these materials lendthemselves readily to a lucid demonstration of the many advantagesarising from the combination set forth. Many dififerent plastics,however, can be used to obtain the same or similar results and inherentadvantages. Combinations effectively used for example are saran andvinyl, polypropylene and polyethylene, or polyethylene terephthalateresins in combination with vinyl or poly-vinylidene chloride.Polypropylene and polyvinylidene chloride would serve similary as wouldpolyamides and polyethylenes. Also, high density polymers of ethylene incombination with a low density polymer of the same plastic are equallyeffective. In the combinations mentioned, the first resin may be appliedin emulsified form to a continuous layer of the second, and in eachinstance, a substantial difference in the melting points of thematerials to be combined is desirable.

Generally, plastics having a higher melting point also show a relativeincrease in density. As a result, the carrier laminae in the compositecushioning materials produced in accordance with the instant invention,usually also provide outer surfaces having a high degree of resistanceto abrasion, pressure and stress. Furthermore, the greater density inthe carrier laminae, makes the resultant cushioning materials imperviousto gases, particularly if a vinylideine chloride polymer is used.

From the preceding description, it becomes quite evident that themethods and resultant products described present a number ofconsiderable advantages in that the invention provides greaterefficiency in manufacture, while the qualities of the multi-laminatesare significantly enhanced.

While only certain embodiments of this invention have been illustratedand described, it is understood that modifications and alterations maybe made without departing from the true scope and spirit thereof.

What is claimed is:

1. A composite plastic cushioning material comprising a first layer, asecond layer overlying and adhered to said first layer, a third layerhaving a plurality of embossments surrounded by unembossed portions anda fourth layer overlying said third layer and following precisely theembossed and unembossed portions of said third layer, all of said layersbeing hermetically sealed one to another, the first and fourth layersbeing of a high density high melting point plastic substantiallyimpervious to gases and said second and third layers being of a lowdensity low melting point resilient plastic, said high density plasticbeing selected from the group consisting of polyvinylidene chloride andpolyethylene, and said low density plastic being selected from the groupconsisting of polyethylene, polypropylene, and polyethyleneterephthalate.

2. A composite plastic cushioning material according to claim 1 whereinsaid high density plastic has a melting point of about 375 F. and saidlow density plastic has a melting point about 230 F.

References Cited UNITED STATES PATENTS 1,997,389 4/1935 Palmer 1611272,978,006 4/1961 Clemens 161-127 3,231,411 1/1966 Tyler et a1. 161-254MORRIS SUSSMAN, Primary Examiner.

